First Order Transitions and Multicritical Points in Weak Itinerant Ferromagnets
First Order Transitions and Multicritical Points in Weak Itinerant Ferromagnets
It is shown that the phase transition in low- ${T}_{c}$ clean itinerant ferromagnets is generically of first order, due to correlation effects that lead to a nonanalytic term in the free energy. A tricritical point separates the line of first order transitions from Heisenberg critical behavior at higher temperatures. Sufficiently …